Electric Flux

A cube of side L=2.0 m is centered at the origin, with the coordinate axes perpendicular to its faces. Find the flux of the electric field [tex]\overrightarrow E = \left( {15{\rm{ N/C}}} \right){\rm{\hat i + }}\left( {{\rm{27 N/C}}} \right){\rm{\hat j + }}\left( {{\rm{39 N/C}}} \right){\rm{\hat k}}[/tex] through each face of the cube.

Thanks. I'm glad I got the units right then.
Can someone look over this and tell me if I did it right? Did I get the signs right? It's the first time I've done this type of problem, and the answer isn't in the back of the book.